Well. really, this is basically ripped off from idea of Steak au Poivre.

Use nice meaty slabs of Ahi Tuna
Rub a bit of Tamari Sauce for the saltiness over the flesh
Crack a bunch of whole peppercorns so that they're broken, not ground;
You can use the bottom of askillet or metal measuring cup, or the side of a chef's knife
Coat both sides of the fish with a healthy layer of peppercorns.
Sear in a hot skillet for just 3-4 minutes, on each side.

Serve with whatever rice and veg you like.

I once made a simple melange of edamame beans and pearl onions with basmati rice.